How to Make a Good Product...with Calculators 

lol green "x" and red checks, what happened to intuitiveness? 🤔

It's a bit ironic that a video on design uses red checkmarks and green crosses lol

A good number of those are made for accounting not engineers - the calculations are immediate. Hence from their standpoint of totaling long lists of values, the plus key will be used a lot more than the equals at the very end... for which we go back to an important part of the first question "does it function well (for the target audience)?" (Those probably don't even need the equals key to work "52/7=" or "52/7+" the operation key sends the previous value, and likely shows the current amount before you start typing the next value)

Nice, informative video! I want to add that as a person who uses a calculator as part of my work, I use the mr(c)/m+/m- keys every day. They are necessary for the calculator audience. I think they should also be included on children's calculators with the hope that they're going to be taught how to use them. The C/CA distinction will let you chose between clearing either the most recent entry, or all entries in general. C is great for correcting keying errors without having to start the calculation again. CA clears all so you can start a new calculation. Hope this helps!

I love how he slowly descends further and further into madness

1. Flex circuit boards have become much more common and reliable in recent years, so making a single flex board that runs the length of the product to accommodate a "neck bend" is not a manufacturing challenge at all. 2. Putting a solar panel below the keypad is complete idiocy. Where is the user's hand going to be? Over the panel, blocking the light. 3. Memory functions are a huge time saver and must-have on a calculator. Imagine measuring floor area of rooms in a house. For each room, you enter "length X width = M+". When you're done with all rooms, MR gives you the area for the whole house. 4. Not mentioned: Are key presses properly debounced? Bounce is an electrical trait that shows up as accidental double key presses. Cheap calculators with poorly debounced keypads are pretty much useless.

I love how passionate you are about the solar panels in the calculator, which is why it pains me to tell you the some of them are a lie. They are just black pieces of plastic, only there to increase the calculators perceived value. I learned this a couple of years ago from fellow calculator lover and youtuber Matt Parker. You should check your calculators to see if any of them are fake

The plus key is actually the most used one, because it initiates the next addition but also finishes the one before, so it’s the same as „=“ then „+“

I can hop online a find a man ranting about calculators. What a time to be alive!

The red check-marks confused me. I like the video, wanted to add that perhaps the memory function is used by some target audience that is important for the seller. In general, I think that if you design a product, those are great discussions to have. He does seem to make himself the target audience, by saying things like "this is too formal". But I understand that it makes a better video if you don't have to say "it depends on who is your target audience" every sentence.

I like this channel a lot and I i definitely agree with the 4 check box points. But man I disagree with so many of your assertions in this video. I think the thing this video showcases best is that knowledge of the target market for your product is key to defining whether or not you've hit your check box.

Those memory buttons probably make a lot more sense to people that use these calculators on a day-to-day basis. One possible design philosophy is "don't design for the beginner, design for the advanced user" which is very valid and is probably more useful to the accountants that use these. The same goes for needing a manual. If you really want to make something new and useful, often you cannot make it obvious and you will require the user to read a manual. Any sufficiently advanced tool will require you to read a manual of some sort. That ugly blue calculator may have had a brilliant feature that you would have known about if you got over your pride and RTFM.

The guy who has used engineering calculators says no product should require a manual 😂 I appreciate the discussion, and a number of the points are valid when discussing commodity products. But there is a place for more complicated solutions at a higher price point. To prove my point... engineering calculators. Which, if you read the manual can help you ace your test and do it quickly. I hate calculus and matrix operations and my calculator can do it for me.

so you are an engineer, run a 3d printing company, make a review of calculator design and cant figure out how the memory buttons work?

"...everyone knows how to use a calculator..." except for you, apparently xD

It is a good thing you are not trying to sell the calculator that you want to design. That calculator would hardly be better than just doing the math in your head. Apparently I am old school, but I used to use calculators as part of my job. The memory buttons were a critical component of their use. The different clear functions depended on if you were trying to clear a number entered erroneously before you hit "=" or clear everything in your current calculation. Your philosophy of not wanting to have to read something to use it has merits towards keeping things simple, but limits you on allowing for complexity. Personally I would like to see on those big red buttons the words "LAUNCH" and "ABORT LAUNCH".

Thanks for all the tips and tricks it helped me a lot in my journey to becoming a better designer/printer !

AC = All Clear, C = Clear, CE = Clear Error, MC = Memory Clear, MR = Memory Read, M+ = Add to memory, M- = subtract from memory

Good and interesting analyses, but I would point out that there might not always be sufficient light to power the solar panel, so having a battery makes sense.

I really love the level of energy throughout the video and how much you care. That's real dedication to great design :D

Love the green "yes" ✖️ (x-es) and red "no" ✔️ (checks).

All valid points, but I feel it's just you who's never figured out how to use the memory functions in a calculator.

Some points: -On mechanical calculators/cash registers, the crank is not the equals key, but the plus key. There is no equals equivalent, as it is not needed. -On many if not most calculators, the solar panel is fake. Solar calculators don't work well indoors unless you still have incandascent light bulbs, so they went out of fashion. The solar panels never were able to charge the battery. - Double zero is very useful for entering prices in cents.

I will note that memory buttons are definitely useful if you want to do more complex math or math with long numbers. Can you remember an 8 digit number in your head? Do you think you can remember a number for a bunch of minutes, especially if you get interrupted during the task? They are always there because yes, there is a use for them and yes, people use them.

An engineer should always consult with the user of the product. Theres a reason the layout is the way it is. In accounting we have to add up a lot of items quickly, that's the reason why the plus sign is bigger. In that case the equal button is actually less used. Since the add button also functions as an equal button since it also displays the sum on the screen

Why do you use a "X" as an approval mark and a "√" check mark for disapproval? That is not logical to me...

The orange calculator reminds me of devices designed by Braun. IMHO Braun employed excellent human factor designers.

Well done! Finally, someone who understands.

Eh, I just have a drawer full of button batteries and they all have the size engraved on them. Not sure what the gripe is. Not putting them on a shopping list is a personal problem, not a product design problem.

Dieter rams and Philippe Starck would probably add nuance!

No one beats Dieter Rams on (amongst others) calculator design: the ET66. Steve Jobs apparently was a huge fan of him.

Suggestion for product that could be fun to have a fresh perspective on: Guitar It has expert and non-expert users, it has manufacturing and UX challenges. You have the standard look and experience people expect, but if you take step back, it's quite a horrible experience to use. My fingers can't really do some chords because it makes my wrist hurt, it's fragile, often expensive, etc. Perhaps that's a bit too much of a design challenge, so if you're looking more for a simple consumer products that has to do one thing: waste bins (how the lid opens), tooth brush, thermostat.

I use the memory keys, but I think you are right about intuitiveness of them. They should have better labeled them so people can better understand how to actually use them.

Most calculator chipsets do the same features. All the designer needs to do is use a reference design, design the keypad and the case around the device. Most chipsets support a solar cell, if the cell is included by the designer. Lay out the keyboard around the reference design and make millions of them.

I think "+" can be the primary button. Adding a bunch of numbers all in one go is something that is the primary use case for many buyers of these simple little machines. They will even show intermediate results when + is pressed, so you can go all day without pressing "=". I also suspect the Casio has a heat bonded ribbon internally. I have certainly taken apart a Sharp where the layout didn't seem to require a ribbon, and yet one was found. Apropos Sharp and era allegedly before product design. The mid 80s brushed metal face designs, i think they are BEAUTIFUL. Thinking of EL-506P. Yes this one is quite visually noisy but it's an engineering calculator which has an advantage of being extra small, it can't be helped. It's an actual pleasure to hold. I think the use in trade is also the reason for 00 button, so people can ignore the decimal point and use 00 instead. For most other uses 00 button doesn't make sense but 000 does. Of course only a chunk of the world trades in units-and-cents and a lot of it does not... so basically you have different types of users for a 4-function calculator with different requirements.

Maybe you should design a calculator and let the viewers critique it.

Observations. There is no reason for either an on, or an off button on a solar powered pocket calculator. When you take it out of your pocket, it gets enough light to turn itself on. When the panel stops getting light, it turns off. A microcircuit could be included that allows the calculator to retain enough of a capacitive charge to handle a few calculations, in a room that's too dim to power the calculator on, but is bright enough to read the display, but that should be limited to 10 seconds of display after the "=" button is pressed. C button (power on in low light state, but this should be a buffered action for any button. If the calculator is in error, it functions as a CE or Clear Error. button If you're in the middle of a calculation, say 1+10, and you intuit that it's going to be 11 w/o hitting the = button, it clears the 10. and displays a '+' for the current 'function, and '1' for the first value. Press C again, it clears the display to a '0' no function. Agree on dropping the 'Mr, M+, M-, and MC' buttons. If we needed a master of ceremonies, I'm not going to carry it in my pocket. Likewise there is no need on a pocket calculator for Square Root, or Percent buttons. There might be a need for the percent button in a business, but if you're not doing financial transactions, it's very rare that you will need that feature. There is a valid reason to do 'order of operations as entered' rather than PEMDAS, however Every instance I've seen is related to inventory, which means it's applicable to financial. In this case, having the '%' key might be interpreted as 'this calculator is too stupid to do PEMDAS, but that seems to me to be the only good use of that key on a pocket calculator. (Side note, the 'valid' reason for an 'as entered' order of operations on a calculator that doesn't have parentheses buttons is, I have 5 cases of 24 spools of black filament, and 3 spools that are loose, Each spool is 2.2 lb, that gives me 5*24+3*2.2 lb of filament on an inventory calculator. Perhaps instead of 2.2 lb, you charge $15 per spool, so the value of the inventory is 5*24+3*15.00 represented in dollars. The problem becoming that if you do this calculation as pemdas, you're going to get the wrong value unless the 5*24+3 is wrapped in parentheses. That and 'we're too dumb to do the mdas portion of pemdas so you're going to get a broken calculator' are the only reasons I can see to do those things. I do consider inventory entry to be a good reason to include the option, but it's a deal breaker for a huge number of math problems. The other option here is to make the + and = functions live on one key as '+=' ) '=' should not repeat the last two steps of the calculation if pressed a second time. I.e 3*35 = should display 105. If you hit '=' again, you should see 105, not 3675. Note that I read off a formula written in standard notation i.e. something like (4*8)/(2-7)= that the comp sci instructor posted to the blackboard, in RPN. as fast as he had put that formula on the blackboard. 4_8*2_7-/ using '_' to 'enter' the value. without looking at the HP 10C in my backpack. So yes I'm familiar with that, and no I don't suggest that this is the best way of teaching math. It's handy for letting comp-sci students understand how the CPU performs the calculations, but beyond that it's mostly just a form of showing off. So, yeah, I was showing off, but if you impress the toughest profesor in your area of study, it can turn out to be helpful, or give you harder homework in the end. We're basically down to 10 digits, +-x/= and a decimal point an a C button as the only buttons really needed on a pocket calculator. 17 buttons, make the '=' button 3 buttons wide under the '0' button that becomes double wide. + gets to be double tall, and next to the = and '.' buttons. -, x and / (division sign) stack as single buttons above those. Lightly contrasting buttons darker than the shell for numbers, a different shade for functions, and yellow for '=', gentle curve at the top that hides the solar panel from view, while lifting the display to an agreeable angle. and you've got a decent pocket calculator. Optionally, celebrate the solar panel on the surface, perhaps taking the space of that missing power and memory row of buttons, and put a flip down 'foot' at the top back of the calculator to give the lift, yet leave the calculator slim for pocket storage. You could probably throw together a virtual version in Javascript, Python, TK, Scratch, or whatever modeling software you like to work with. I refuse to do so after looking at way too much javascript implementing a basic calculator about 30 years ago. I know some people who might implement something like this in hardware using capacitive touch buttons. I'm not a big fan of those, but if it floats your boat, go with it. Considering the target market, I'd consider using a snap together front and back plate, with buttons etc., that aforementioned flip down foot, (robustness would be an issue though) and a TPU bumper around the entire calculator that would help to protect the buttons from accidental presses while it's in your pocket, and give you something comfortable to hold in your hand if you don't have a table or desk to set the calculator on. The extra 'grip' would be nice, and if you did it in a high contrast green, orange, yellow or purple, you might not be going to the store the next day to get another one as often. There might be a market for bumpers that handle turning that flat calculator into a wedge for readability though... Is it perfect, Um, no! it's just a stripped down and made attractie basic calculator. You can do everything it can with paper and a pencil. And be able to show your work untill the teacher tells you to show your work on why 3x5=15. (I'm presuming the class this week isn't trying to show options where the values are octal (result 17), or hex, (F).

Gabe: "Today we'll talk about product design" Also Gabe: 15:32

I love this kind of video! It'd be cool to have you review submitted community product designs too if this type of video continues :)

I actually enjoyed this video format idea 👌🏻 would love to see more of this, I enjoy these videos applying them to fabrication manufacturing especially when making up kits for clients to be installing them selves

I love these kind of videos, it gets your brain going. I see your point but there is a very good reason to use Lithium batteries over AA or AAA: short shelf life, they will likely go bad before they are spent and replaced. Having to clean battery muck is not a good user experience. I would say that, if you use a button battery, go for a CR2032, the ones PC motherboards use, they are the easiest to find.

The M buttons on a calculator can actually be very useful in specific circumstances!

Very good video and thought process breakdown. I think a cool follow up video would be you designing a calculator for additive manufacturing. Critique others work, then show us how you would do it.

Never thought i would see a video on rating calculator designs.

Ce is clear error. Which allows you to clear an erroneous input without losing your entire equation. It's probably the most important button on a calculator if you have fumble fingers LOL

For other product reviews, consider lamps. Should they turn on/off by touch, clapping, push switch, rotor switch, or via remote control.

Excellent video; it's like a year of product design courses in less than half an hour. I will be watching this again 🤓🤓. PD: Art is the conscious and constant search for perfection. So, engineering and design can be art - and anything, really, as long as you're striving for perfection.

Thank you. Perfectley presentead.

if you've never used those buttons, I really have to question your engineering chops .

I didn’t think I would get so much enjoyment about a video on calculator design. Can you pull apart the white/purple one to see if a solar panel only one has a battery somewhere inside? …. Now I want to design a calculator hahaha

Well explained. Would be nice to see your design of a calculator. Where can we see some products/designs your company created to have a glance at a good design from professionalists ?

Those solar panels are not real.

This rant sounded like a critique from an interior decorator who has never used a calculator rather than an engineer. Anyone who does not know how to use memory and clear functions is not a real calculator user.

I liked this video, did't miss 3D printing. I would suggest you do 66% 3D printing 33% product design videos

Maybe a solar panel is more expensive than a button battery? 3V coin cells are readily available and the CR2032 is extremely common and cheap. Also, I think that 3V can directly power some chips. The coin cell is thin and light weight, and an LCD device can last for a year or more on one battery. The solar panel needs illumination to operate and takes up space on the front panel. Using a AAA battery is a bad idea I think since it is heavy, fat, needs a big spring connector, and needs a voltage booster or multiple cells. Enjoyable video!

8:29 While it's true having an angled display is more expensive, there are so many options nowadays that I'd say it's hardly a manufacturing concern. It's mostly only a cost related consideration. You can run a lcd off of 4 wires, those can be a ribbon, or you could use 2 fancy connectors and something flexible in between. Heck, you could go for a flex rigid pcb, and save yourself assembly time. 🤷‍♂️ Casio is obviously the cheapest, but being cheap nowadays is often not the best way to sell most profitable.

Design the perfect calculator, bonus points for 3d printable and cherry MX switches.

Boy you sure can tell the generational differences. I bet Gabe never saw a vintage HP scientific calculator. Just ribbing you. As usual, a great video.

fyi. the plus key also functions as a equal key in every scenario I could come up with. At least on my calculator.

I think it's genuinely an interesting video, basicly displaying how a "simple" product can vary is such a vast amount of ways. And that's just "regular" calculators, add "scientific" or "engineering" or "desk" or "accountant" to your search terms will give you a whole new set of designs. Which... is probably why they all are made SO cheaply, there is simply just so much competition on this market. About the larger + sign... Generally, you don't NEED to use the = sign that much, adding a lot of numbers together, you'll just press the value, +, next value and in the end, the + will work as a "= and +" so.. it's more efficient to just use the plus. Especially if you're unsure if you have to add more stuff into your total. Like adding totals in a pile of reciept as you go along. About the memory keys: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-WzePMBCHMhA.html It's for doing complex calculations on a calculator without brackets. It's basicly just using the memory as a single variable where you can add whatever result you have on the display (M+) or subtract (M-) to whatever you currently have in memory. If nothing, you simply add or subtract from 0. MR will display what's currently in memory, and the MC is basicly just memory clear. -As someone who works in IT I've never used it myself either, but I've helped a lot of finance people to know how a lot of them work. :)

1+2+3+4=10 I used the equal key once, but the plus key three times 🤨

NO WAY HE SPOKE ABOUT CALCULATERS FOR 30MIN STRIGHT

Those aren't usable calculators! Only 1 memory? No geometry functions? No PI or E(xp) button? No scientific notation? Not programmable? What the hell can you do with that which an abacus wouldn't do better? ;-)

Funny how long you rant about the memory button but didn't take the 3 minutes to google and find out how to use it.

hp35 had very small keys, it was great. small keys were small enough so when you won't hit 2 keys at once. But it was new in 1970 and was one of the first great scientific calculator without programming.

i wouldn't want anyone talking to me the way he talked to that poor amazon calculator

You Sent me on a deep Dive into what the PLAY BUTTON DOES lol Well here is name and usage "Right shift key" Shifts the displayed value to the right, deleting the rightmost digit. Also the CE button is for clearing an error if the calculator can't compute the entry and display and ERROR message on screen you press the CE button to clear just the error screen and take you back to your entered value whereas the on/off/clear button will clear everything

Better term than simple: elegant I've been finding more and more that there's a big difference between simple and elegant. But they often look the same outwardly.

You talk about a calculator user should not have to read the instructions (figuring out AC, C, CE, and the memory functions) but you also talk about your use of graphing calculators. Did you not read the instructions for the graphing functions? At what level of complexity is reading instructions allowed?

I often find myself simply adding up values, but i never trust the result unless i can verify that i didn’t miss or mistype any value. Therefore the part, which I find essential for a basic calculator (which also replaces the memory function) is the history tape. On iPhone i use the app „solves“. Design-wise it’s very okay. It also has a two-column-wide zero, brackets, percentage and a column of divide, times, minus, plus and equal. These buttons are highlighted. Guess which button is not highlighted? The C. And i think it’s fine. It doesn’t have an “on” anywhere either, because obviously you don’t have to start after opening the app. But why does nobody think similarly about a hardware calculator? With solar nobody cares about an off button. Why not similarly make any it turn on with any button?!

Oh boy, you would LOVE my building’s intercom system that has an instruction manual to the side with FOUR STEPS to be able to ring the right doorbell for my apartment. It has only numbers, so for getting apartment “9-A” you would have to input 91 and then a bell shaped button. I refer to it as my personal sphinx: solve the riddle and show me you are worthy to enter my home 👹

Calculators are a bad choice for the point you're trying to make. They are a tool that is used to get the job done, and function is far more important than form. When I look at a calculator that has put form first, like the green one you showed, I will test it by putting in 3 + 3 x 3 =. If it doesn't say 12, it's garbage and useless. (3+3=6x3=18, yes, but in math, you do the multiplication first--order of operations--so it's really 3x3+3=9+3=12.) And do you really expect us to take advice from someone who chose red checks to say a calculator has a feature and a green x to say it doesn't? Talk about not being intuitive.

Actually, I disagreed with you on many of your points. If I worked for you, I would watch the video, tell ya it was great, and then ignore it for the rest of my life. Simple and intuitive we agree on though, but what that looks like, not so much.

I had a calculator back in school that was aranged like you where describing. No "M" hocosbocos it had sin and csin butons instead. The on buton was red and only had a big C on it no OFF buton it turns off after like 5 min of not using it, the = buton was big. And all butons where a bit rounded on the edges. Just... it was like an unclean dark green color with light green butons. Tough it had AAA batteries no solar panel.

So, change the design from something utilitarian that gets the job done for a busy person, to something for an emotionally unstable person who barely knows what math is or how to use it but makes them happy to be around it? Sheesh. 20 years from now people will look at what we're making today with all the disdain that you have for the old Casio....or they'll be too stupid to even know what math is and will have to ask their phone what 2+2 is.

As an engineer, I disagree with you on MOST of your points. I guess its all about "eye of the beholder" issue. If you don't know something "READ THE INSTRUCTIONS" Why? Safety, basic knowledge of item use, basic instructions of item. So yea, Instructions are needed... This Post/discussion is more about "YOUR OPINION ONLY". Not about how to make a good product in general...

Button batteries are absolutely the most confusing "system" and is just chaos.

I'm still trying to figure out how he didn't notice the "Play" and "GT" buttons on the forest green calculator.

6:07 m+/m- add/sub to the memory. An accumulation variable.

i like that the X is green to pass and the V is red to say it fails , counteract each other ... as for the memory function , i use it a lot as it get used to store middle calculations ( like (15 + 20) - 15 + (20 - 5 ) ) so the m+ ( positive value ) get used to store the temp solution the M- is for negative value's so you can calculate positive and negative value's . AC = All Clear C = Clear ( no memory clear ) MC = Memory Clear ( only memory ) GT ? Grand Total ? no idea .. play button ? hope i shows a youtube video .. but got no idea..

Right off the bat. The plus button also functions as an equals button and is the most commonly used operator on this style of calculator. Its place and size are functionally optimal. Memory functions here are the most rudimentary way of doing bracketed calculations or keeping running totals. I use them all the time. The Chinese calculator's solar panel is in the worst place possible. Right under your hand, in the shadow. Although if you pop it open you'll probably find it's just a piece of glass and isn't even connected. cmon, man. bitching about commonly used functions on a calculator you don't use, because you don't know how to use them, is weak. Casio has been doing this for half a century, and makes different styles of calculators for different use cases. They know what they're doing. The only button I miss from most of the base level calculators is a [1/x] button. So you can take your result and divide something by it without having to use the memory. Scientific calcs are great and all, but the UI us usually awful for doing rapid-fire arithmetic, which is what these pocket and desk calculators are made for.

Do you even need an On button? Pressing any button already turns them on.

equal ? what the heck this key is about ? - a rpm hp user ;c)

10:05 have to say this. This brand is from China where the number dilimination is by 10000 so 2 0s is kind of useful also for real only accounts use caluculator these days to that 00 probably is useful to some extent. as most transaction that is more than 3 digit probably have 2 00s such as 100.00 (also 2 decimal precision, so 00 also helps here)

Another thing: you complain about the plus button being not orange on the nice orange calculator. I guess it’s a matter of cost: this way you only need one run to make the ‚0’ and ‚=‘ button. The more buttons share same shape and color, the cheaper it gets

Just because you can't handle basic calculator buttons is a weak argument for not having them there. Maybe it's an argument that... ;-P

The "expensive" texture on the back of the purple calculator was probably done with a laser. Which means not that expensive

How about reviewing the rumble jar go? It's a cold brew coffee maker with features that stand out to me. It would be interesting to hear your thoughts on it vs other cold brew systems.

Why don\'t you tell us how you really feel about the Amazon Basic calc!!! :)

2:33 funny to me how we don't need a label for what a door handle does, but we need a clip in your video to show us a door and door handle working. 😆

I honestly never really understood the solar panels on calculators since these are mostly used indoors. When you're not using the calculator, you're just going to throw it in a random drawer, so it won't charge. In my opinion, a calculator with a battery is way better since those last for years before the battery dies, and people are probably going to lose the thing or forget about it before that happens. When I went to high school, I needed to buy a calculator, which I have used very extensively. I still have it and it still turns on, even though I bought it over 10 years ago and it doesn't have a solarpanel. I do have to say that I don't know how long it takes to charge a calculator with a solar panel. I think it won't take that long, but even if it takes like a second, I still think a battery that lasts for more than 10 years is better.

8:58 You just said the equals was the most used button..well which is it 🤔 also, the buttons on this one don't differ terribly much from the previous, yet this one is intuitive and the other isn't? 🧐 That's not to say stuff can't be learned from the video, but..bruh..

You made this video for monetization..there fixed it for you.

10:06 you missed the point of 00. In some kind of machines with 0 and 00. Double pressing 0 is clear.

did i just watch a video reviewing cheap calculators? 🤣.... I appreciate some of the framing for your evaluation metric, but I was really hoping you were going ot deliver more on the "how to" part of the video title. Also, was a bit disappointed there wasn't at least some mention of Dieter Ram's 10 principles, even if you wanted to condense them into your 4 points.

I'm trying to build a studio that uses your instruction in an effort to use your farm.

Damn i didn't realise how much calculators sucked.

6:48 Hey, I'm colorblind and that calculator is still pretty darn ugly hahaha

Wait till this guy sees the ti 84+

I would take a button battery o er aaa anytime as they will last a long time and not leak acid destroying the calculator.